Current-controlling means



Jan. 12 1926. 1,569.372

L.C.F.HORLE CURRENT CONTROLLING MEANS Filed July 17 1924 nu NH 1 WWW HWH Patented Jan. 12, 1926.

mwnnncr: c. r. HORLE, or NEWARK,

PATENT OFFICE.

NEW JERSEY, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO FEDERAL TELEPHONE MANUFACTURING CORPORATION, OF BUF- FALO, NEW YORK, ACOBPORATION OF NEW YORK.

CURRENT-CONTROLLING MEANS.

Application filed July 17, 1924. Serial No. 726,642.

' To all whom it may concern:

Be it known that I, LAWRENCE C. F. HORLE, a Citizen of the United States of America, and a resident of Newark, county of Essex, and State of New Jersey, have invented certain new and useful Improvements in Current-Controllin Means, of which the following is a speci cation.

This invention relates to an improved form of current controlling means adaptable readily to various circuits diifering widely as to the voltage drop across them and as to the value of current traversing them. More particularly, the invention relates to a current controlling means which obviates the necessity for the provision of a variety of rheostats to meet difiering voltage and current requirements over a wide range. v

An example of the problem involved in attempting to provide current control means where the current consuming devices to be controlled vary widely as tovolta e drop and value of current, and where a current supply sources of a variety of voltages may be used, is met with in the operation of vacuum tubes. Heretofore current con-- trolling means for use with vacuum tubes I have been constructed with a narrow ran e 0 of control, and suitable only for tubes fair y uniform as to filament voltage and current. But with the rapid increase in the number of tube types dlfiering greatly in filament voltage and current, the narrow range controlling means has become inadequate, re-

' quiring, as it does, that a number of rheostats varying as to resistance and current carrying capacity must beprovided, each best suited in any given installation, to type 40 and number of'tubes and to type of battery 7 or other current source supplying the heating current for the filaments. It should be noted that the combinations of filament *voltage and currentnow encountered, and

to which the current controlling means must be adapted, are numerous, and also that tubes vary considerably as to the ratio of voltage to current. For example, a list of tubes in common use shows the following figures for filament voltage and current: 5 volts, 1 ampere; 5 volts, .25 ampere; 1.1 volt, .25 ampere; 3 volts. .060 ampere. To add further to the difiiculty of adapting the controlling rheostat to the widely varying tube filament requirements, the introduction of low filament voltage and low filament current tubes has meant a considerable variation in the range of voltage of the source of filament current, 'usually batteries,

sity for providing a number of rheostats to suit different tubes.

The object is accomplished for the particular case of the vacuum tube cited, and for similar cases where a number of current consuming devices of different voltage and current characteristics have been heretofore controlled by rheostats of different size, by the provision of a resistance element consisting of a plurality of resistance members connected in series.

The following drawings and description fully and clearly explain the principle and application of the invention.

Fig. 1 is a diagram showing a resistance element in a circuit in which is included a current consuming element and a source of current.

Figure 2 is a plan view of one form of the invention. I

Figure 3 is a side elevation of Figure 2.

Figure 4 is a cross section on line A A of Figure 2.

Figure 5 is a. plan view of another form of the invention.

In the figures the same part will be designated by the same reference character wherever such part is shown in several views: ,7

In the diagram of Figure 1, a resistance element 1 is shown as made up of two sections in series, one, for example, a heavy wire section 2 and the other a ne wire section 3. The element 1 is shown as part of a current controlling device 4, and as connected in circuit with a current consuming element 7 5 which in the present case is the filament of a vacuum tube, and in circuit with a source of current 6 which in the present case is a battery. In the embodiment of the invention shown in Figures 2, 3, and4, the resistance element 1 is shown as mounted on an insulating and supporting member 7, which is set into the recess 8 of the insulating base 9. A rotatable metal sleeve 10 passes through base 9 and is held in position by plate 11 and by springwasher 12. Con tact plate 14 is staked securely to sleeve 10 and rotates with it. Contact finger l5 bears on the resistance wires mounted on member 7. A shaft 16 passes through sleeve 10 and is fastened thereto by set screws 17. Two terminal plates 18 and 19 are fastened to base 9 by screws 20 and 21 respectively. The free end of the heavy wire section 2 of resistance element 1 is connected to terminal plate 18, the connection being made by looping the end of the wire of section 2 under the head of screw 20. Sleeve 10 is connected electrically to terminal plate 19 through plate 11, and screw 21, said screw 21 serving to fasten both plate 11 and terminal plate 19 to base 9.

In operation, leads of a circuit,such as il-.

lustrated in Figure 1 and containing a current source and a current consuming device, are connected to terminal plates 18 and 19. The current-path through the rheostat is then as follows: terminal 18, screw,

, and one of fine wire may occupy approximately equal space on the supporting member 7 although this is not. essential. In order to carry into effect the objects of the invention, the two sections 2*and 3 are formed respectively of wire of such material and cross section that the current carr ing capacity of section 2 is materially hig er than that of section 3, and the resistance of sec described, since more than two sections may be used in making up the resistance element.

'next the medium-wire section 24, and finally the fine-wire section 25.-- As in the case of the two section construction, the three sections of element 22 are connected in series.

The other details of construction and o ration are the same essentially-as described for the two section arrangement. A rheostat constructed in accordance with my invention and carrying the subdivision of the resistance element to three sections, as shown in Figure 5, may have the following resistance element characteristics: Current carrying capacity of sections 23, 24 and 25 respec-, tively may be 2 ampe'res, 1 ampere and .25 ampere; resistance of sections 23, 24 and 25 respectively may be, 1.5 ohms, 4 ohms and 54.5 ohms, or a'total resistance ofelement 22 of 60 ohms. Considering the three sections as they compare with each other in current carrying capacity, and in resistance: The current carrying capacity of hea -wire section 23 is materially hi her than t at of medium-wire section 24 (a ut twice in the case illustrated in Figure 5); the current carrying capacity of medium wire section 24 is, in turn, materially higher than that of .fine-wire section 25 (about four times in the case illustrated) but the resistance of heavy-wire section 23 is materially lower than that of medium-wire section 24 (about .4 in the case illustrated) the resistance of medium wire section 24 is, further, very materiallylower than that of fine-wire section 25 (about .07 in the case illustrated).

It will be seen that in both the two-section and the three-section arrangement of the resistance element, the current carrying capacity of this element is stepped up, so that the section having low carrying capacity is at the free end of the resistance element and the section having high carrying capacity is at the terminal end of the resistance .ele-

ment (terminal 18 in the figures). on the other hand, the resistance .per section is stepped up toward the free end of the resistance element, so that the section of low resistance is at the terminal end of the element (terminal 18) and the section of high resistance is at the free end. I

Used with a current'consuming device, for example the filament of a vacuum tube, or a plurality of such filaments, having a lar voltage drop and requiring a comparative y large current, a rheostat constructedin accordance with my invention will utilize on] the heavy-wire section, or a portion thereo and no other section. But if used with some current consuming device, for example, the

filament'of a small vacuum tube, having a small voltage drop and requiring only a small amount of current, the rheostat will utilize all of the sections including such portion of the fine-wire section as is needed to bring the current to the desired value.

It is evident that'these extreme cases and a large variety of other cases between these extremes are within the range of a current controlling means constructed in accordance with my invention, merely by adjusting for the proper amount of resistance. In the embodiment of the invention shown in the figures this adjustment is easily accomplished by the rotatin of the contact finger over the resistance ement.

What is claimed is:

1. In a rheostat, a basemember carrying a resistance element comprising in series a comparatively heavy wire coil and a comparatively fine wire coil, a rotatable sleeve journaled in said base and adapted to be fastened to an actuatin vshaft and carrying a contact finger in sli able engagement with said resistance element, and means associated with said base and independent of said shaft for holding said sleeve and attached finger in alignment with respect to said base and said resistance element.

2. In a rheostat, a base member carrying a resistance element comprising in series a comparatively heavy wire coil and a comparatively fine wire coil, a pair of terminal plates mounted on said base, a rotatable sleeve adapted to be fastened to an actuating shaft and passing through said base and having a bearing therein, a contact plate fastened to said sleeve and having a contact finger in slidable engagement with said resistance element, and means associated with said base and independent of said shaft for holding said sleeve and attached finger in alignment with respect to said base and said resistance element, said means comprising a contact strip on one side of said base in engagement with said sleeve and with one of said terminal plates and comprising a spring member on the opposite side of said base and in engagement with said sleeve.

In witness whereof, I hereunto subscribe my name.

' LAWRENCE C. F. HORLE. 

